... ,construction, mining Material: ABS, PE, PP, HDPE is available Color: red, blue, yellow, white, black, orange is ok Rib: one rib ... , two ribs and three ribs on the top of shell could be done Lock type of back hoop: Turning knob ... , ratchetColourRed, Yellow, WhiteSize52-60CMFeatures· Safety helmet with a versatile new shell design of V rib with 6 cooling vents on top ...